3D Printer Troubleshooting Guide: 15 Common Problems & How to Fix Them
Your printer was working perfectly yesterday. Today it has apparently chosen violence.
Most failed prints leave clues. Find the problem that looks like yours below, tap it, and jump straight to the troubleshooting steps.
Tap the Problem That Looks Like Yours
Tap any image to jump straight to the troubleshooting steps.
The PEWgilist troubleshooting rule: Change ONE thing at a time. If you change temperature, flow, retraction, speed, and Z-offset all at once and the next print works, great—you fixed it. You just have absolutely no idea what fixed it.
1. First Layer Won't Stick
What it looks like: Filament will not stick to the build plate, gets dragged by the nozzle, or the print breaks loose.
Check first: Clean the build plate, check Z-offset, verify bed mesh/leveling, confirm the correct bed temperature, and make sure the first layer is not printing too fast. The nozzle should be close enough for adjacent lines to bond without being so low that extrusion is restricted.
PEWgilist Tip: Before coating the plate in enough glue to hang drywall, figure out why it is not sticking.
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2. Filament Not Extruding
What it looks like: The printer moves normally, but little or no filament comes out.
Check that the spool is not tangled, filament can travel freely, the extruder is gripping it, and the hotend is at an appropriate temperature. Then manually extrude filament. If the extruder tries but filament still does not flow correctly, continue to the clogged-nozzle section.
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3. Clogged Nozzle
What it looks like: Very little filament comes out, extrusion becomes inconsistent, or the extruder clicks or skips.
A restriction is not always a completely plugged nozzle. Heat the hotend appropriately for the loaded material and test extrusion. Inspect the filament path and extruder before assuming the nozzle needs replacing. Printing faster than the hotend can melt material can also mimic under-extrusion.
PEWgilist Tip: A small problem can look surprisingly similar to a “take the whole printer apart” problem. Do not start with option two.
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4. Stringing & Oozing
What it looks like: Fine hairs or spiderwebs stretch between separate areas of the model.
Check filament moisture first, especially with PETG. Then verify nozzle temperature, retraction, and travel settings. Excessive temperature can increase oozing. Change one variable at a time.
PEWgilist Tip: Do not spend an hour perfecting retraction settings on filament that needs drying. Your slicer cannot dehydrate plastic.
If moisture may be the problem, see our How, When & Why to Dry 3D Printer Filament guide before tuning retraction around wet filament.
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5. Warping & Curling
What it looks like: Corners or edges lift from the build plate.
Check first-layer adhesion, bed temperature, drafts, and cooling. A brim can add contact area. Materials with greater thermal shrinkage, such as ABS and ASA, may benefit from a controlled environment or enclosure. PLA, PETG, ABS, and ASA do not all behave the same way.
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6. Under-Extrusion
What it looks like: Gaps between lines, thin walls, missing material, or weak parts.
Possible causes include a partial clog, low temperature, extruder slipping, incorrect flow calibration, excessive speed for the hotend's available flow, or a filament/profile issue. Check the physical filament path and nozzle before using flow settings to hide the symptom.
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7. Over-Extrusion
What it looks like: Bulging lines, rough surfaces, poor dimensional accuracy, or excess material.
Verify the correct filament profile and check extrusion/flow calibration using the procedure recommended for your printer. Do not randomly lower flow because one model looks ugly. Diagnose first; adjust second.
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8. Layer Shifting
What it looks like: Part of the model suddenly moves sideways.
Check belt tension, pulleys, obstructions, smooth axis movement, cables or filament interfering with movement, nozzle collisions, and excessive speed or acceleration.
PEWgilist Tip: If your Benchy suddenly looks like it hit an iceberg sideways, start with the mechanics.
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9. Layer Separation
What it looks like: Layers split apart or horizontal cracks form through the model.
Check nozzle temperature, cooling, extrusion, drafts, and the surrounding environment. Printing too cold can reduce interlayer bonding, while excessive cooling can hurt adhesion with some materials. A print can look good and still be mechanically weak.
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10. Elephant's Foot
What it looks like: The bottom layers flare outward wider than the rest of the model.
Check first-layer squish, Z-offset, and bed temperature before reaching for slicer compensation. Correct the physical cause first when possible.
PEWgilist Tip: It is called elephant's foot. Your printer has not developed a medical condition.
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11. Blobs & Zits
What it looks like: Small bumps appear on otherwise smooth walls.
See whether they line up with the seam. Investigate seam placement, retraction, temperature, pressure/flow behavior, and filament condition. If the bumps are random, do not automatically blame the seam.
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12. Ringing / Ghosting
What it looks like: Repeating ripples appear after corners, lettering, or other sharp features.
Check belts, fasteners, printer stability, speed, and acceleration. On printers that support it, follow the manufacturer's resonance or input-shaping calibration procedure.
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13. Poor Bridges & Overhangs
What it looks like: Unsupported sections sag, curl, or turn into a stringy mess.
Check cooling, nozzle temperature, bridge speed/settings, geometry, and material. Run a small bridge test instead of sacrificing another six-hour print to the filament gods.
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14. Supports Hard to Remove
What it looks like: The model printed successfully, but the supports seem to have signed a permanent lease.
Start with support interface and contact/Z distance. Too little separation can fuse support to the model; too much can hurt the supported surface. Then review density and support style. The goal is enough support to print successfully and still come back off.
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15. Poor Surface Quality
What it looks like: Rough, uneven, wavy, or inconsistent walls.
Work systematically: filament condition → temperature → extrusion → mechanics → speed → nozzle → slicer settings. Do not assume a smaller layer height will fix an extrusion or mechanical problem.
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Before You Tear the Printer Apart...
Ask yourself: What changed? New spool? Different filament? New slicer profile? Different temperature? Printer moved? Nozzle changed? Firmware updated? Was the last print actually good?
Sometimes there is nothing wrong with the printer. Moisture, unsuitable temperature, inconsistent feeding, or the wrong filament profile can imitate machine problems. If you suspect moisture, start with our filament-drying guide.
One Last PEWgilist Rule
Do not change everything. Make one meaningful change, run a small test, look at the result, and move to the next variable.
Because there are two types of 3D printer owners: people who have had failed prints... and people who have not been printing very long.
Keep printing.
— PEWgilist Supply Co.